Description

This command begins a new transaction block. If the isolation
level, read/write mode, or deferrable mode is specified, the new
transaction has those characteristics, as if SET TRANSACTION was executed. This
is the same as the BEGIN
command.

Parameters

Refer to SET
TRANSACTION for information on the meaning of the parameters
to this statement.

Compatibility

In the standard, it is not necessary to issue START TRANSACTION to start a transaction block:
any SQL command implicitly begins a block. PostgreSQL's behavior can be seen as
implicitly issuing a COMMIT after each
command that does not follow START
TRANSACTION (or BEGIN), and it is
therefore often called "autocommit".
Other relational database systems might offer an autocommit
feature as a convenience.

The DEFERRABLEtransaction_mode is a PostgreSQL language extension.

The SQL standard requires commas between successive transaction_modes, but for historical
reasons PostgreSQL allows the
commas to be omitted.